It is a common practice to transport freight in containers. The containers are relatively large structures that are transported by rail, truck, and ship to designated locations. Material handling machines are used to move the containers in freight yards and load and unload the containers from railroad cars, ships, and trucks.
The material handling machines have spreaders adapted to be attached to the top of the containers. In one type of machine, the spreaders are pendently supported from a box-shaped frame, known as a gallows, with a plurality of chains. Hydraulic cylinders extended between a fixed member and the container are used to swing the spreaders relative to the gallows to position the container in a desired location. The gallows and suspended spreader have considerable height, so that it cannot be used in a confined environment, such as below a deck of a ship. The elevating capacity of the machine is limited to the elevated height of the lift apparatus of the machine. The gallows and spreader cannot independently lift the containers to a desired location.
A load handling mobile machine having a tall L-shaped boom is disclosed by Larsen and Robnett in U.S. Pat. No. 4,016,992. A load carriage assembly is rotatably mounted on the boom. The high profile of this machine prevents its use in restricted spaces. Copie in U.S. Pat. No. 4,268,216 discloses a load lifting and carrying machine having a load support unit attached to a spreader frame with pivoted attaching members. The load support unit has a relatively high profile which restricts its use to unconfined environments.